Tuning means for receiver sets



' Patented Oct. 5, 1937 UNITED STATES 2,094,751 I TUNING MEANS FOR RECEIVER SETS Hans 0. Roosenstein, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application May 29, 1934, Serial No. 728,102 In Germany June 29, 1933 Claims.

In building receiving sets which are intended for the reception of a great number of broadcast stations or other stations, it is customary to arrange the names of these stations upon a scale 5 provided on the drive means of the tuning device in a clearly visible manner. In other word's,the attempt to locate a desired transmitter station and the tuning thereto is reduced to the labor of finding the name of the station in the list on the scale'ordial, and once this has been accomplished, setting may be efiected. Hence, the sequence of the list of station names is chosen according to the frequency or wave length of such stations. Such an arrangement, of course, renders immediate location of the desired station more difficult. 4

'Now, the present invention facilitates a rapid location of the desired station in that ways and means are disclosed whereby reference may be had to a plan of the station disposed on the receiving set in which the designations" of different stations are indicated in such a manner that immediate and speedy location is feasible, for instance, in an alphabetical or geographical sequence. In this latter case this plan assumes the appearance of a map. The latter may suitably be distorted, though'in such a way that the position of any desired stationviill be readily discernible. This plan or map presents a number of spots or openings which arecoordinated to different transmitter stations, and each of these spots according to desire may be'coordinated to a locking device adapted to lock or arrest the motion of the tuning device such as a rotary or variable condenser, variometer, or equivalents upon the setting corresponding to the desired station having been reached. The said arresting or locking device most suitably may consist of a plug or peg inserted into an opening in the plan or map corresponding to the desired station, the end of said plug being caused to engage or snap into a corresponding depression or notch formed in a drum rigidly connected with the tuning device, upon the desired point or setting having been attained.

For abetter understanding of the invention reference is made to the accompanying drawing, in which: i

' Fig. 1 is a sectional View of a tuning indicator made according'to the invention tog'e'ther'with a schematic diagram of certain circuits associated therewith,

Fig. 2 is asectional view showing the preferred 5 construction of the stop device, and

Fig. 3 is a sectional view of a modified form of stop pin and drum.

- One exemplified embodiment of the device of this invention is schematically illustrated'in Fig. 1, where l denotes the front panel of the receiving set. The plan of the stations is arranged upon a plate 2 fixedly supported inside the housing or box, for instance, in the form of a geographical map. In the form of construction here shown by way of example, the said plate 2 has the form of a cylindrical segment which may be supported at each end from the side walls of the housing, not shown, by suitable means such as the army and bracket 2. The holes 3 therein formed designate difierent transmitters or broadcast stations. At the locations at which, for example, two stations are located twoholes may suitably be provided. The spindle or shaft 4 of the tuning device, such as a variable condenser having rotor plates 30, isfin rigid connection with a drum 5. This rigid connection may take the form of a pair of radial spokes 5 disposed at opposite, sides of the drum, the inner ends of each pair of said spokes terminating in a hub or bushing d which is keyed fast to the shaft 4, and the outer ends of the spokes being fastened to the inner surface of the drum. Only one pair of spokes 5 and the associated hub t are shown. The movable drum 5 has a plurality of holes 6 each of which latter corresponds to a single and particular hole 3 coordinated thereto in the plan or map so that it will come to register therewith when the corresponding station is tuned in. Furthermore, each hole 6 must be so arranged that the distance which it travels from the original position until it comes to register with the corresponding hole 3 in the map will correspond to the requisite movement of the rotary condenser until proper tuning has been secured. It will be understood that the holes 3 are distributed over the area of the map, one hole being at the position of each desired transmitting station and that a corresponding registering hole 5 is provided in drum 5 for the corresponding tuning position of thereceiver. The movement of the drum 5 and conjointly therewith of the tuning device 30 may be accomplished subject to the action of a spring 1 the inner end of which is attached to a lever 91, while the outer end thereof bears on an anterior stop 3i provided on the drum 5. The lever 9 isrigidly connected with the drive flange or drum 8 by any suitable means, such as the radial connecting arm and bracket 9. There is moreover secured on the circular drum 8 a plate H) in the form of a cylindrical segment which,

in the initial position may serve as a cover for the plan or map 2, and upon the displacement or shifting of drive drum 8 as a switch means designed to close and make several circuits, for example, by way of the contacts II, I2. Members 32 project rearwardly from panel I to provide an opening through which the map may be viewed and terminate close to iii to form a closure therewith.

In order to actuate the tuning device, the driving flange 8 is moved by hand in the downward direction as shown by the arrow until the station plan 2 becomes entirely visible. When in this position, the cover plate I0 closes the contacts II by way of which the receiver power supply terminals 33 are connected with the supply line or current mains M. Another suitable plan is to cause simultaneously two illuminating lamps I3, I4 to flash up (by the agency of contacts of a suitable sort not indicated in the drawing). Next the desired station is selected by inserting a plug I5 in the hole 3 corresponding to such desired station in the plan or map 2. The said plug I5 has at its anterior tip an elastic pin I5 pressed outwardly by spring 34 which upon striking against the slide 5 will slide on its surface until the corresponding hole 6 has been reached, into which it will then engage with the result that all further movement of the drum 5 is blocked. The movement of the latter and of the tuning device after insertion of the plug I5 in the selected hole 3 of the map, for example, may be effected by that upon further rotation of the drive flange or knob 8 the tension of the spring I will overcome the friction whereby the movement of the drum 5 is retarded. Upon further rotation of the flange IIl into its end position, during which the drum 5 is held in the station tuning position by plug I5, the contacts i2 finally are closed whereby the loudspeaker circuit 35 is connected with the receiver audio output terminals 36. Inasmuch as this is accomplishable only after the setting to the desired station, only this particular station will be heard upon completion of the tuning. The member 31' fastened to a suitable fixed support (not shown) represents such an end stop for drum II! which may be held in this end position by knob 8 under control of the operator, or by any known form of brake means (not shown). It will of course be understood that for a new setting of the tuning mechanism, the plug I5 is removed and the drum 8 restored to its starting position of rest where the plate I!) covers the scale or dial drum 3, and the procedure above described repeated for the new station. In the return movement of the drum 8 the lever or arm 9 will in its backward movement in a clockwise direction abut against the stop 3I of the drum 35 and carry the latter to its initial position.

In an arrangement as hereinbefore described in detail, after insertion of the plug in a hole 3, manual operation will be necessary for initiating the movement of the tuning means, namely, the pulling of the driving drum 8. Hence, this arrangement may be termed to be of a semi-automatic nature.

As a general rule, the frequency dependence of the standard type of condenser is not quite exactly reproducible in order that with the receiving arrangement here disclosed an exact tuning to the desired station may be readily obtainable. In order to overcome this drawback and provide a Vernier control one suitable plan would be to dispose the pin I6 eccentrically rather than in the geometrical axis 2I of the plug I5 as shown inIig. 3, and to make the holes 6 of the drum 5, for example, rectangular. The result is that by the turning of the plug I5 in the hole 3 about its geometric axis 2! the incidentally caused motion of the eccentric pin IE will occasion a slight shift of the drum 5 and rotor plates 30. Another way adapted to cause slight corrections in tuning and setting consists in the use of a parallel operating tuning means, say, another rotary condenser with a very low maximum capacity.

In case stations are intended to be received with an arrangement as hereinbefore disclosed that are not indicated on the map, the locking means may be rendered inoperative in that the plug I5 is inserted into the opening 22 in casing I intended therefor. As a result the switch contact 23 will be closed so that the loudspeaker 31 is connected with the receiver terminals 36. By a simple twist or turn of the collar or drum 8 it will then be an easy matter to insure any desired tuning or setting. In order that also in this kind of tuning any desired station may be readily identified, a station name list may be suitably disposed upon the drive element, say, flange or drum 8 in the 'usual manner, such list bearing the station names arranged according to frequency.

Having described my invention, what I claim as novel and desire to secure by Letters Patent is:

1. In combination with a tuning means, a sta-.

tionary member provided with a plurality of apertures, a movable member connected to said tuning means and provided with an aperture, said last named aperture corresponding to a predetermined position of said tuning means a plug insertable through an aperture of said stationary member and having an outwardly spring pressed extension frictionally engaging the surface of said movable member and automatically insertable in the aperture of said movable member under the action of said spring at the predetermined position of said tuning means. 7

2. In combination with a radio device provided with a panel member having an aperture, a tuning means positionedat the rear of said panel, .a station indicating means mounted behind said aperture and associated with said tuning means, a power supply circuit for energizing said device, a rotatable member connected to said tuning means and arranged to close said aperture in one position of said tuning means and to close said power supply circuit in another position of said tuning means.

3. In combination with a radio device having a pair of output terminals, a rotatable tuning means, a member connected to said tuning means and rotatable therewith, a power supply circuit for energizing said device, said member being arranged to close said power supply circuit in one position of said tuning means, an output circuit including a sound reproducer connected to said output terminals and means whereby said rotatable member closes said output circuit upon: further rotation of said tuning means.

4. In combination with a radio device having a pair of output terminals, a rotatable tuning means, a metallic member connected to said tuning means and rotatable therewith, a power supply circuit for energizing said device and having a pair of terminals arranged to contact said metallic member in one position of said tuning means, an output circuit including a translating device and a pair of terminals connected in series to said outputterminals, said last named pair of terminals being so located as to be in engagement with said metallic member only after the latter has been rotated through more than 180 degrees.

5. In combination a panel, a shaft mounted be hind said panel and parallel thereto, a tuning reactance connected to said shaft, a lever journalled for free rotation on said shaft, a control knob rigidly secured to said lever and having a portion extending in front of said panel, a stop means connected to said shaft and. arranged to stop it at a predetermined position of said tuning reactance and a yieldable spring connecting said lever and stop means, said stop means being provided with an abutment arranged to engage said lever to thereby limit the rotation of said stop means in one direction.

HANS. O. ROOSENSTEIN. 

